Fuel Injector DIY, anyone...? Options

[Prospectfarms]

A few months ago I replaced 2 leaky injectors with new from Now one of the remaining originals has stopped delivering fuel. I assume it's clogged. I don't want to buy another one if I can clear this one. Anyone done it at home? redharvey uses a 3 volt transformer and carb cleaner: http://www.914world.com/bbs2/index.php?s=&...t&p=1514533
Anyone else?

[wingnut86]

With 35 year old injector's, assume the worst and hope for the best.

I agree with other's recommendations on WitchHunter...

[Valy]

Carb cleaner, US bath and new filters and they should be like new, except for corrosion damage.

[Prospectfarms]

U.S. = ultrasound. Thanks.

I replaced the others 'cause I thought leak-down meant they were irreparable. This injector won't spray so maybe it can be "cleaned."

I'd prefer not to wait a week by sending it out or buying new. I also don't want to spend $ I don't have to, so I'm interested in trying reharvey's procedure. He doesn't describe what he does it in the post, but I'm guessing you open the injector with a little juice and then spray the heck out of it.

Searching this topic, you come across the issue of internal screens. Can anyone describe how to access those, and where to source them? Sounds unlikely to me.

What's up with having your local "diesel shop" clean the injector, as referenced in related threads? Is there a better term for these 'cause I'm not clear on what they are? Garage, machine shop, other? Should I just look for a building with lots of Macs and Freightliners in the parking lot?

I've cleaned my own injectors for many years using a can of carb cleaner and a dc train transformer set to 3 volts to fire the injector with very good results. It's not something I would recommend to everyone but it works for me.

[reharvey]

Wow--someone found that comment I made about cleaning my own injectors. Like I said it's not for everyone to try because all kind of bad things can go wrong. Go buy rebuilt ones.

[SLITS]

If it's not spraying, it could be a bad / dead solenoid. It should "click" when power is applied. They also will have a resistance across the terminals of 2.5 ohms.

The machine that does them holds them open (powered) and a cleaning solution is run through them. A leak down test along with a flow test is performed. Leak down is applying a known pressure to see if the injector leaks at all (not powered) under pressure. If it leaks around the plastic to metal barrel interface, it is tossed. If it leaks through the pintel, you can try cleaning it again.

A flow test (cc/min) is then performed to see if it is close to the manufacturers' specification.

I once set up a fuel rail ( two injectors). Used a common pump (single in, single out) with a container of cleaning fluid, and a stock pressure regulator. All cleaning fluid was returned to the container. I set 30 lbs pressure and then triggered the injectors and let the cleaning solution run through them for 8 hours. I could also watch the spray pattern of the injectors. The only thing I couldn't do was change the micro-screen in the inlet of the injectors (didn't have a supply of them.

it would also be nice to be able to run the cleaning fluid in the opposite direction .. backflushing as it were.

[Prospectfarms]

Wow--someone found that comment I made about cleaning my own injectors. Like I said it's not for everyone to try because all kind of bad things can go wrong. Go buy rebuilt ones.

No thanks, I'm comfortable with explosions. So you apply 3V and then just start working it over with the carb spray? Is there an audible cue that indicates when the injector has opened?

[Prospectfarms]

If it's not spraying, it could be a bad / dead solenoid. It should "click" when power is applied. They also will have a resistance across the terminals of 2.5 ohms....

it would also be nice to be able to run the cleaning fluid in the opposite direction .. backflushing as it were.

TX Slits, for the solenoid resistance specs and good description of your cleaning set-up. I agree about back-flushing. Maybe reharvey sprays both ends?

[Prospectfarms]

Well I mined back to that last page of search results. Here's what airsix did: http://www.914world.com/bbs2/index.php?s=&...ost&p=18798

<!-- QuoteBegin-porsche735+Apr 25 2003, 01:16 PM --><div class='quotetop'>QUOTE(porsche735 @ Apr 25 2003, 01:16 PM)</div><div class='quotemain'><!-- QuoteEBegin --> What is the best way to make sure the injectors are free of crap on the inside?  Can you just yank them, spray some brake cleaner in them and blow them out with air?  Is there a better way?

Chris <!-- QuoteEnd --></div><!-- QuoteEEnd -->
If you really want to get the crud out you have to cycle the injector solenoid while pushing a cleaning solvent through the injector.

I backflushed an old set by wiring the injector up to a battery and momentary-on switch. Then I could push the button to open the injector (click!). I've been going to build a nice injector cleaning fixture but what I did last time was just wire up the injector like this, then lightly clamped a length of 3/8" fuel hose over the injector nipple (careful! Don't break the plastic nipple). Then I filled the hose with carb/choke cleaner and pressurized the hose with 10psi regulated air from a rubber tipped air nozzle. Now with the line full of solvent and pressurized I give the battery switch little taps (click, click, click) to backflush solvent through the injector. Stop when only air comes out. I caught the solvent in a clean bottle to see what came out. All of them spit out some debris - one spit out a lot.

I'm embarrased to even describe the technique because it's so Rube Goldberg, but it worked. Next time I need to clean injectors I'll make a nice little rack with a fuel rail and o-ringed bungs etc. etc. Or better yet maybe I can find or borrow a real injector cleaner for cheap. We'll see.

-Ben M.

ps - I don't want to underemphasise that if you do this be careful not to break the injector nipples. They are sheathed in plastic and if you crank down on a hose clamp on one I'm sure it will break. I haven't broken any, but I've seen injectors with broken nipples and they don't look all that sturdy.